Hi. I have always been a fan of fish from a small age, but I always had tropical set-ups. I now have a cold water tank. I recently exchanged a small 2' tank for a much larger 4' tank. The tank currently now contains 3 small goldfish and 2 small ghost koi (which are being fattened up to go in a much larger pond at the new house). My questions is this: I also have in the tank 2 small weather loach, but they are never anywhere to be found. I originally bought them to give some life to the base of the tank. Before I shell out for more of these social little things, I wanted to know if it was a good or bad idea to add more in order for them to be more visible and prominent in the tank? Or are there any other cold water fish which would be more suited to my tank set-up? The filter system is advanced with under cupboard filter, 2 foot spray bar to the back. Also a dual air-line pump which is connected to 30cm air stones, which span the back of the tank at the base. As a separate issue, my tank is running a little warm due to the room temp, is there any way to combat this? Or would my current stock of fish be ok with a temp of around 76f/24c? Thanks in advance, hope you can help.